The CTT Rating does alot of stuff that can't be talked about outside of the rating. Most likely, the recruiters that you had didn't know what to tell you. They don't know themselves unless they are a cryptologist. Really the only way is to do some research online and look at what is available. Thats really all your going to be able to do until you get to Pensacola.
These are good links of information.
http://usmilitary.about.com/library/milinfo/navyjobs/navyjobs2/blctt.htm
http://usmilitary.about.com/library/milinfo/navyjobs/navyjobs2/blewaef.htm
Good luck in your future career in the world's greatest Navy.
CTT3 Michael Taylor, USN